DESCRIPTION OF PROJECT: The inflammatory bowel diseases (IBD) are chronic immune-mediated conditions of the gastrointestinal tract that include Crohn's disease and ulcerative colitis, affecting ~1.1 million Americans. Both conditions affect individuals throughout their life span, with a peak incidence in the second and third decades of life. Despite the availability of medical therapies, the long-term prognosis of IBD is widely heterogeneous. Over the last 2 years, our collaborative group, comprised of investigators at the Massachusetts General Hospital in Boston and local investigators in Rhode Island, have been working with the Centers for Disease Control and Prevention (CDC) and the Crohn's &Colitis Foundation of America (CCFA) to pilot OSCCAR (the Ocean State Crohn's &Colitis Area Registry) a novel, population-based, prospective inception cohort of inflammatory bowel disease in the state of Rhode Island. The goal of this project has been to establish and maintain a population based, prospective cohort of patients newly diagnosed with IBD in the state of Rhode Island in order to describe the incidence of IBD in the US and to develop models that accurately predict disease prognosis. Having established the foundational methodology to assemble this unique cohort, we seek to continue our collaboration with the CDC and to expand enrollment and duration of follow-up in the cohort in order to identify variables associated with clinically important outcomes. We proposed continued collaboration between the CCFA and the CDC in enrollment and follow up of newly diagnosed patients with IBD in our OSCCAR cohort in Rhode Island. Over the next 5 year period of funding, we anticipate having sufficient power to identify predictors of important outcomes, such as steroid-dependence and disease complications such as stricture and fistula, and the effects of variations in treatment on these important outcomes. Unique to this cohort, the use of prospectively collected data will help to avoid the issue of confounding by indication that would be unavoidable in the analysis of purely retrospectively collected data. To complement our approach in Rhode Island, we propose to utilize the existing framework of the National Health Interview Survey to obtain prevalence data, and to increase the geographic, racial and ethnic diversity of the population data available for IBD in the US. Capitalizing on this long-standing surveillance system administered by the CDC will allow us to obtain representative random sampling of the U.S. population, including under-represented minority populations to identify trends in the epidemiology of IBD in the U.S. In summary, we plan to leverage the growing resources of the OSCCAR cohort and the well-respected expertise of the CCFA, with its prior success in collaboration with the CDC, in advancing the cause of individuals affected by IBD to accomplish broad-reaching epidemiologic research initiatives. Taken together, the proposed studies will provide a robust representation of the burden of inflammatory bowel disease on the population of the United States, and more importantly will serve as a foundational basis for practice improvements that could lead to improved outcomes.